1. Field of the Invention
The present invention relates to a disk drive, and more particularly, to an actuator latch apparatus for a disk drive, in which an actuator is locked in a specified position when a disk is not rotating, such that the actuator is prevented from arbitrarily rotating due to an impact to the disk drive.
2. Description of Related Art
A hard disk drive (HDD) is a device for reproducing/recording data from/on a disk using a read/write head. In such an HDD, the read/write head moves to a desired position while moving above a recording surface of a rotating disk by means of an actuator and executes the reproducing/recording functions.
When the HDD is not in operation, that is, when the disk is not rotating, the head is parked off the recording surface of the disk in order to prevent a collision with the recording surface of the disk. Such head parking systems can be classified into a contact start-stop (CSS) system and a ramp loading system. In a CSS system, a parking zone in which data is non-recordable is provided in an inner circumference of the disk and the head is parked in close contact with the parking zone. In the ramp loading system, the head is parked on the ramp, which is located outside the disk.
While the head is parked on the parking zone or the ramp, the actuator may arbitrarily rotate due to an impact to or vibration of the HDD, such that the head is forced out of the parking zone or the ramp and on the recording surface of the disk. In this case, the head may make forceful contact with the recording surface of the disk, such that the head and the recording surface may be damaged. Therefore, when the head is parked on the parking zone or the ramp, the actuator must be locked in a specified position so that it cannot rotate arbitrarily. For this purpose, various kinds of actuator latch apparatuses are provided in the HDD.
FIGS. 1A through 1C illustrate a single lever type inertial latch apparatus according to the conventional art.
Referring to FIG. 1A, a HDD includes an actuator 10 for moving a read/write head to a specified position on the disk. The actuator 10 includes a swing arm 12 rotatably mounted on a pivot 11, and a suspension 13 installed in one end portion of the swing arm 12 to elastically bias the slider 14 toward a surface of the disk, in which the head is mounted on the slider 14.
The HDD further includes an inertial latch apparatus 20 for locking the actuator 10 when the head is parked in the ramp 15. The inertial latch apparatus 20 includes a latch lever 21 rotating due to inertia, a latch hook 22 provided on a front end of the latch lever 21, a notch 23 provided at the swing arm 12, a crash stop 24 limiting a clockwise rotation relative to the apparatus 20 as depicted in that figure of the swing arm 12, and a latch stop 25 limiting a clockwise rotation of the latch lever 21.
According to the conventional inertial latch apparatus 20, as shown in FIG. 1B, when a rotational force impacts the HDD in a clockwise direction relative to the apparatus 20 as depicted in that figure, the swing arm 12 and the latch lever 21 rotate in a counterclockwise direction due to inertia. Thus, the latch hook 22 is caught by the notch 23, such that the swing arm 12 cannot rotate further. Conversely, as shown in FIG. 1C, when a rotational force impacts the HDD in a counterclockwise direction relative to the apparatus 20 as depicted in that figure, the swing arm 12 and the latch lever 21 rotate in a clockwise direction due to inertia. At first, the swing arm 12 rotates in a clockwise direction, but it collides with the crash stop 24 with a reaction, resulting in the swing arm 12 rotating in a counterclockwise direction. The latch lever 21 collides with the latch stop 25 with a reaction, resulting in the latch lever 21 rotating in a counterclockwise direction. The latch hook 22 is engaged with the notch 23, thereby locking the actuator 10.
Such a single lever type inertial latch apparatus 20 operates correctly when the swing arm 12 of the actuator 10 rotates in a counterclockwise direction due to a clockwise rotational force impacted to the HDD. However, when a rotational force impacts the HDD in a counterclockwise direction, both the swing arm 12 and the latch lever 21 rebound, such that the latch hook 22 and the notch 23 are locked to each other. In this case, if the rebounding timing of the swing arm 12 and the latch lever 21 do not match correctly, the notch 23 is not locked to the latch hook 22. As a result, the actuator 10 is not locked. In other words, the conventional art inertial latch apparatus has a drawback in that a locking reliability of the actuator 10 cannot be guaranteed.
FIGS. 2A through 2C illustrate a dual lever type inertial latch apparatus, which is an improvement of the single lever type inertial latch apparatus.
Referring to FIG. 2A, an inertial latch apparatus 40 for locking an actuator 30 includes two latch levers 41 and 42 rotating due to inertia, a latch pin 43 provided at the first latch lever 41, a latch hook 44 provided at the second latch lever 42, a notch 45 provided at a swing arm 32 of the actuator 30, and a crash stop 46 limiting a clockwise rotation of the swing arm 32.
According to the dual lever type inertial latch apparatus 40, when a rotational force impacts an HDD in a clockwise direction relative to the apparatus 40 as depicted in that figure, the swing arm 32 and the first and second latch levers 41 and 42 rotate in a counterclockwise direction relative to the apparatus 40 as depicted in that figure due to inertia, as shown in FIG. 2B. Therefore, the latch hook 44 is locked to the notch 45, such that the swing arm 32 does not rotate further. On the contrary, as shown in FIG. 2C, when a rotational force impacts an HDD in a counterclockwise direction relative to the apparatus 40 as depicted in that figure, the swing arm 32 and the first latch lever 41 rotate in a clockwise direction due to inertia. At first, the swing arm 32 rotates in a clockwise direction relative to the apparatus 40 as depicted in that figure, but it collides with the crash stop 46 with a reaction, resulting in the swing arm 32 rotating in a counterclockwise direction. The first latch lever 41 rotates in a clockwise direction and the latch pin 43 causes the second latch lever 42 to rotate in a counterclockwise direction. The latch hook 44 of the second latch lever 42 interferes the notch 45 such that a counterclockwise rotation of the swing arm 32 is limited.
The dual lever type inertial latch apparatus 40 operates stably with respect to the rotational force impacting the HDD in the clockwise and counterclockwise directions. However, since the dual lever type inertial latch apparatus 40 requires two latch levers 41 and 42, its structure is complex and its size is large, such that it occupies a large area. Also, a manufacturing cost is increased and much time is necessary to assemble it. Therefore, the dual lever type inertial latch apparatus 40 is difficult to apply to a small-sized mobile disk drive.
The above-described conventional inertial latch apparatuses 20 and 40 operate with respect to a relatively strong rotational force enough to rotate the latch lever. That is, when a relatively weak impact or vibration is applied to the HDD, the latch lever operating due to inertia does not rotate, such that the actuator is not locked but rotates arbitrarily. Therefore, a locking reliability of the actuator cannot be guaranteed when a weak impact is applied to the HDD.